Acarbon dioxide generator orCO2 generator is a machine used to enhancecarbon dioxide levels in order to promote plant growth ingreenhouses or other enclosed areas.[1][2] Carbon dioxide generators have been used to help grow marijuana.[3][4] They can be fueled withpropane ornatural gas. CO2 generators were used mostly by commercial growers until smaller and less expensive systems made the technology more widely available to hobbyists.[1] The generators also give off heat.[5] Using compressed CO2 is an alternative to generators.